The emergence of experimental economics in the last third of the 20th century revisited the long-standing belief that economics is a non-experimental discipline. The history of this new practice reveals this went further than simply introducing the experimental method to economics. Its history shows individual economists and research communities above all redefining the relationship between economic theory and rigorous data. Replicable data that were specifically created to satisfy conditions set by theory in controlled environments could not be avoided by economists or explained away as irrelevant to economic theory. The reconceptualization of the relationship between economic theory and rigorous experimental data culminated at the end of the 1980s in what I call the experimental turn, after which the experimental method became accepted in the wider economics community.